Feature: 'pinned' buffers similar to chrome tabs (#145)

* Feature: 'pinned' buffers similar to chrome tabs

* Add help docs for BufferPin command and options

* Remove the pin_status option

README.md

@@ -130,6 +130,8 @@ nnoremap <silent>    <A-6> :BufferGoto 6<CR>
 nnoremap <silent>    <A-7> :BufferGoto 7<CR>
 nnoremap <silent>    <A-8> :BufferGoto 8<CR>
 nnoremap <silent>    <A-9> :BufferLast<CR>
+" Pin/unpin buffer
+nnoremap <silent>    <A-p> :BufferPin<CR>
 " Close buffer
 nnoremap <silent>    <A-c> :BufferClose<CR>
 " Wipeout buffer
@@ -234,6 +236,7 @@ let bufferline.icon_separator_active = '▎'
 let bufferline.icon_separator_inactive = '▎'
 let bufferline.icon_close_tab = ''
 let bufferline.icon_close_tab_modified = '●'
+let bufferline.icon_pinned = '車'
 
 " Sets the maximum padding width with which to surround each tab.
 let bufferline.maximum_padding = 4
@@ -301,6 +304,7 @@ vim.g.bufferline = {
   icon_separator_inactive = '▎',
   icon_close_tab = '',
   icon_close_tab_modified = '●',
+  icon_pinned = '車',
 
   -- Sets the maximum padding width with which to surround each tab
   maximum_padding = 1,

doc/barbar.txt

@@ -47,7 +47,8 @@ The name of each command should be descriptive enough for you to use it.
    nnoremap <silent>    <A-7> :BufferGoto 7<CR>
    nnoremap <silent>    <A-8> :BufferGoto 8<CR>
    nnoremap <silent>    <A-9> :BufferLast<CR>
-
+   " Pin/unpin buffer
+   nnoremap <silent>    <A-p> :BufferPin<CR>
    " Close buffer
    nnoremap <silent>    <A-c> :BufferClose<CR>
 
@@ -199,6 +200,11 @@ Here are the groups that you should define if you'd like to style Barbar.
 	The button used to close the tab when it has been modified since
 	last save.
 
+			                         *g:bufferline.icon_pinned*
+`g:bufferline.icon_pinned`                            string (default '車')
+
+	The icon used to indicate that a buffer is pinned.
+
 						    *g:bufferline.closable*
 `g:bufferline.closable`		boolean	(default v:true)
 

lua/bufferline/layout.lua

@@ -49,6 +49,12 @@ local function calculate_buffers_width(state, base_width)
           + 1 -- space-after-buffer-index
       end
 
+      if state.is_pinned(buffer_number) then
+        width = width
+          + 1 -- spacing after filename
+          + strwidth(opts.icon_pinned)
+      end
+
       if opts.closable then
         width = width
           + strwidth(not nvim.buf_get_option(buffer_number, 'modified') -- close-icon

lua/bufferline/render.lua

@@ -148,6 +148,10 @@ local function render(update_names)
     local iconPrefix = ''
     local icon = ''
 
+    -- The pin icon
+    local pinPrefix = ''
+    local pin = ''
+
     if has_numbers then
       local number_text = tostring(i)
       bufferIndexPrefix = hl('Buffer' .. status .. 'Index')
@@ -173,6 +177,11 @@ local function render(update_names)
         iconPrefix = has_icon_custom_colors and hl('Buffer' .. status .. 'Icon') or hlName and hl(hlName) or namePrefix
         icon = iconChar .. ' '
       end
+
+      if state.is_pinned(buffer_number) then
+        pinPrefix = namePrefix
+        pin = ' ' .. icons.pinned
+      end
     end
 
     local closePrefix = ''
@@ -211,6 +220,7 @@ local function render(update_names)
         {iconPrefix,         icon},
         {jumpLetterPrefix,   jumpLetter},
         {namePrefix,         name},
+        {pinPrefix,          pin},
         {'',                 padding},
         {'',                 ' '},
         {closePrefix,        close},

lua/bufferline/state.lua

@@ -20,6 +20,7 @@ local ANIMATION_OPEN_DURATION  = 150
 local ANIMATION_OPEN_DELAY     =  50
 local ANIMATION_CLOSE_DURATION = 100
 local ANIMATION_SCROLL_DURATION = 200
+local PIN = "bufferline_pin"
 
 --------------------------------
 -- Section: Application state --
@@ -56,6 +57,32 @@ function m.get_buffer_data(id)
   return m.buffers_by_id[id]
 end
 
+-- Pinned buffers
+
+local function is_pinned(bufnr)
+  local ok, val = pcall(vim.api.nvim_buf_get_var, bufnr, PIN)
+  return ok and val
+end
+
+local function sort_pins_to_left()
+  local pinned = {}
+  local unpinned = {}
+  for _, bufnr in ipairs(m.buffers) do
+    if is_pinned(bufnr) then
+      table.insert(pinned, bufnr)
+    else
+      table.insert(unpinned, bufnr)
+    end
+  end
+  m.buffers = vim.list_extend(pinned, unpinned)
+end
+
+local function toggle_pin(bufnr)
+  bufnr = bufnr or 0
+  vim.api.nvim_buf_set_var(bufnr, PIN, not is_pinned(bufnr))
+  sort_pins_to_left()
+  vim.fn["bufferline#update"]()
+end
 
 -- Scrolling
 
@@ -140,6 +167,8 @@ local function open_buffers(new_buffers)
     end
   end
 
+  sort_pins_to_left()
+
   -- We're done if there is no animations
   if vim.g.bufferline.animation == false then
     return
@@ -338,6 +367,7 @@ local function move_buffer(from_idx, to_idx)
   local bufnr = m.buffers[from_idx]
   table.remove(m.buffers, from_idx)
   table.insert(m.buffers, to_idx, bufnr)
+  sort_pins_to_left()
 
   vim.fn['bufferline#update']()
 end
@@ -457,34 +487,54 @@ end
 
 -- Ordering
 
+local function with_pin_order(order_func)
+  return function(a, b)
+    local a_pinned = is_pinned(a)
+    local b_pinned = is_pinned(b)
+    if a_pinned and not b_pinned then
+      return true
+    elseif b_pinned and not a_pinned then
+      return false
+    else
+      return order_func(a, b)
+    end
+  end
+end
+
 local function is_relative_path(path)
    return fnamemodify(path, ':p') ~= path
 end
 
 local function order_by_directory()
-  table.sort(m.buffers, function(a, b)
-    local na = bufname(a)
-    local nb = bufname(b)
-    local ra = is_relative_path(na)
-    local rb = is_relative_path(nb)
-    if ra and not rb then
-      return true
-    end
-    if not ra and rb then
-      return false
-    end
-    return na < nb
-  end)
-  vim.fn['bufferline#update']()
+  table.sort(
+    m.buffers,
+    with_pin_order(function(a, b)
+      local na = bufname(a)
+      local nb = bufname(b)
+      local ra = is_relative_path(na)
+      local rb = is_relative_path(nb)
+      if ra and not rb then
+        return true
+      end
+      if not ra and rb then
+        return false
+      end
+      return na < nb
+    end)
+  )
+  vim.fn["bufferline#update"]()
 end
 
 local function order_by_language()
-  table.sort(m.buffers, function(a, b)
-    local na = fnamemodify(bufname(a), ':e')
-    local nb = fnamemodify(bufname(b), ':e')
-    return na < nb
-  end)
-  vim.fn['bufferline#update']()
+  table.sort(
+    m.buffers,
+    with_pin_order(function(a, b)
+      local na = fnamemodify(bufname(a), ":e")
+      local nb = fnamemodify(bufname(b), ":e")
+      return na < nb
+    end)
+  )
+  vim.fn["bufferline#update"]()
 end
 
 
@@ -556,11 +606,13 @@ m.close_all_but_current = close_all_but_current
 m.close_buffers_right = close_buffers_right
 m.close_buffers_left = close_buffers_left
 
+m.is_pinned = is_pinned
 m.move_current_buffer_to = move_current_buffer_to
 m.move_current_buffer = move_current_buffer
 m.goto_buffer = goto_buffer
 m.goto_buffer_relative = goto_buffer_relative
 
+m.toggle_pin = toggle_pin
 m.order_by_directory = order_by_directory
 m.order_by_language = order_by_language
 

plugin/bufferline.vim

@@ -68,6 +68,7 @@ command! -count   -bang BufferMovePrevious     call s:move_current_buffer(-v:cou
 command! -nargs=1 -bang BufferMove             call s:move_current_buffer_to(<f-args>)
 
 command!          -bang BufferPick             call bufferline#pick_buffer()
+command!                BufferPin              lua require'bufferline.state'.toggle_pin()
 
 command!          -bang BufferOrderByDirectory call bufferline#order_by_directory()
 command!          -bang BufferOrderByLanguage  call bufferline#order_by_language()
@@ -96,6 +97,7 @@ let s:DEFAULT_OPTIONS = {
 \ 'exclude_name': v:null,
 \ 'icon_close_tab': '',
 \ 'icon_close_tab_modified': '●',
+\ 'icon_pinned': '車',
 \ 'icon_separator_active':   '▎',
 \ 'icon_separator_inactive': '▎',
 \ 'icons': v:true,